Diuretic drugs, due to their having mild hypotensive effects, have long been clinically used as antihypertensive agents. However, as undesirable side effects caused by the use for a long time, influences on metabolism, for example, hypokalemia, hyperuricemia, hyperlipemia and diabetes melitus, have been taken up. While calcium antagonists have been used as therapeutic agents of circulatory diseases such as hypertension, cardiac diseases, cerebral apoplexy, nephritis and arteriosclerosis, it has also been known that they tend to cause such undesirable side effects as tachycardia, hypotension, erythroprosopalgia and encephalagia, which are considered to be due to their abrupt vasodilative action.
On the other hand, it is disclosed in EP-0425921, EP-0459136 and EP-0520423 that benzimidazole derivatives have an angiotensin II antagonistic activities and are useful for the therapy of circulatory diseases including hypertension, cardiac diseases (cardiac insufficiency, myocardial infarction, etc.), cerebral apoplexy, nephritis and arteriosclerosis. The mechanism of the action is considered that the benzimidazole derivatives inhibit the binding of angiotensin II having a strong vasoconstrictive action to an angiotensin II acceptor. And, while, in JPA H3(1991)-27362 and JPA H5(1993)-132467, it is disclosed that an imidazole derivative having angiotensin II antagonistic action is administered together with a diuretic agent or a calcium antagonistic agent.